What are your priorities?
The biggest decision is iOS or Android. Both have their ardent supporters (but if someone is ardent about a phone operating system, you can probably not worry too much about their opinion on it!)
...My main priorities are reliability, sound quality and battery life. I'd also like email access and gps on it. Other than that, I really have no clue.
...The sound is likely 10 years ahead of what you had in a flip phone.
...Reliability is mostly a factor of who your carrier is. Sprint and T-Mobile suck.
...Your choice is iPhone that costs more, but is simpler/easier to use.
...What've your friends got? Look at those.
..I have been with Sprint since the late 90's. Reliability hasn't been an issue, but the sound quality is. I recently heard that might be because they tend to stretch their cell tower network pretty thin.
...My father got an iPhone 5 last year and switched from Sprint to Verizon. He is very happy with them and the phone. I was leaning towards the iPhone simply because of the fact that my 68 year-old father figured it out pretty quickly. That means there's hope for me.
...My brother, however, is a technophile and he keeps pushing the LG G4. He says it works well across all the carriers, has a ton of great apps and allows you to quickly (and relatively inexpensively) change the battery on your own if it runs down. It sounds a little over my head, but I'm not telling him that. I can't let my little brother get a swelled head by telling him that he's smarter than me.![]()
Battery-wise, the Androids almost always have a user changeable battery

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.